So, I just got a brand new 09 X3 delivered from the dealer that has some swirling. Will this go away with a little time and washing? I always thought these swirls were caused by car washes with brushes. Would the dealer use a buffer that would cause permanent swirling??

Your dealer's prep guy swirled it up unfortunately, the good news is it isn't the paint that's marred, rather, it's the clearcoat that's mildly damaged ( some of the new Nissans actually have clearcoat that heals itself).

You can follow the OP's advice and do it yourself, or you can take it to a really good detailer and have them get the swirls out for you.

I've followed the latter route with many of my new cars simply because I haven't been pleased with how the dealer does it at delivery.